How do you make an if-then statement return a greater value?

From ggc

I'm working on the Logic problem, blackjack. It says to return the value nearest 21. How can you make it return a value nearest 21? Here's what I have but it doesn't work.

public int blackjack(int a, int b) {

 if(a>21 && b>21)
  {
   return 0;
  }
 else if(a<=21 && a>b)
  {
   return a;
  }
 else if(b<=21 && b>a)
  {
   return b;
  }
 else
  {
   return 0;
  }

}

What if both a and b are 21? or if they are both the same?